The present invention relates to a damping device for a contactless, passive, radial support of a rotor rotating at a high rotary frequency, especially of a textile open-end rotor spinning device.
A rotor with passive radial support which is supported in a contactless manner, e.g., magnetically or aerostatically, has the problem that undesired radial oscillations can occur. There is the danger that the oscillations can assume a magnitude at which the radial deflection of the rotor becomes so great that the rotor makes contact with its cushioning bearing or some other close component and therefore a further increasing of the rotary frequency out of the range of the natural resonance is only possible with very great accelerations of speed of rotation or not at all. For this reason support systems are used in such instances which comprise a radial damping of oscillations.
A rotor supported in a contactless manner can be actively damped, e.g., as regards the radial excitation of oscillations. A relatively great expense for the sensory mechanism, actuator mechanism and control is necessary for this purpose.
Another possibility for radial damping of oscillations is in the form of a passive damping of oscillations in which the attempt is also made to reduce the radial deflection. Such a device is known, e.g., from German Patent Publication DE 195 437 45 A1. In this publication, the stator magnet of a magnetic bearing is elastically suspended on spring legs. The magnetic bearing, located on the stator side, is additionally held by a frictional connection which begins to start with friction upon an appropriately large oscillatory amplitude of the rotor and thus effects a damping.
It is disadvantageous, for example, in the case of a bearing arrangement in accordance with German Patent Publication DE 195 437 45 A1, that the compensation of oscillations does not become effective until the oscillatory amplitude has assumed a magnitude at which the friction begins. Before this value at which the friction device begins to operate has been achieved, there is an undamped operation . The damping act ion, which does not begin until later, is opposed by a lastingly oscillation-poor running of the rotor.
A further disadvantage is the fact that the manufacturing of the spring-leg arrangement is very difficult and expensive. Inaccuracies in it result in a radial offset and/or in an error as regards the maintaining of the desired air gap and or in an error as regards the planar parallelism of the bearing magnets, which jeopardizes the operation of the bearing arrangement.
Another disadvantage is the fact that the rigidity of the magnetic bearing is reduced by the rigidity of the spring-leg arrangement. As a result of the fact that the stator magnet fixing the rotor is not completely stationary since it was attached so that it could oscillate, the position of the rotor is inconstant in analogy with the oscillatory movements of the stator magnet. The damping oscillation of the stator magnet can result in an additional impairment of the smooth running of the rotor. An unfavorable superpositioning of the two oscillatory frequencies can not be excluded.
The above-mentioned disadvantages can occur either alone or in combination and an unobjectionable operation of the damping device is present in neither instance.